Method of attaching integrated circuits to a substrate by an electron beam

Abstract

Abstract 1,125,745. Welding by fusion. ENGLISH ELECTRIC-LEO-MARCONI COMPUTERS Ltd. 15 March, 1967 [16 March, 1966], No. 11624/66. Heading B3R. A method of attaching an integrated circuit chip 10 to a plurality of conducting lands 14 on a substrate 13 comprises directing an electron beam through the chip at least in the regions overlying the lands to melt the material of the lands and thereby weld the chip thereto. Suitable material for the lands, with a silicon chip, is a gold-germanium eutectic with 27% germanium. Welding is carried out with the parts in vacuum or an inert atmosphere. The thickness of the chip should not exceed 50 microns in the weld regions which may therefore be provided with recesses 11 of appropriate depth. Welding may be effected with a defocussed beam, preferably with a mask to prevent damage to the active regions of the chip. Alternatively a focussed beam with or without a mask may be caused to scan the chip in a single cycle or a plurality of scanning cycles. The beam may be switched off when not directed at a region to be welded. Damage to the chip by radiation may be minimized by providing a protective coating of e.g. gold on the upper surface of the chip which may also be annealed after welding. In an automatic process the chips are held and located by a jig (20), (Fig. 3, not shown) which also serves as a mask during welding.

Inventors

• 👤 John Beesley
• 👤 Robert Anthony Hyman

Bibliographic Details